ATOM HUB AC/DC, RS-485 VOLTAGE CONVERTER, VOLTAGE PROBLEM



  • I am working on a project where the switch is controlled by the M5 PIR SENSOR.
    When I power the ATOM from USB everything works fine, when I power it with a 12V 3A PSU thought the RS485 voltage converter the PIR begins malfunctioning (fake triggers).

    I checked the voltage of the two groove outputs (from the hub and from the atom lite) under USB and 12V power. As long as USB is connected, the interfaces shows a quite stable 4.98V.
    When the USB is unplugged, leaving only the 12V power source, the voltage drops to 3.3-3.28V, if the atom is removed it goes back to 5V
    I guess this is causing the PIR to misbehave, since it requires 5V.

    What´s wrong?
    According to labels on the components and to the HUB schematics, I expect 5V 2A from the DC/DC converter.

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